I made a parts run down to Oregon this weekend (3 hour drive each way). On the way back, about an hour into the drive, the charge light comes on. I stopped to check it out, all the wires on the alternator were tight. I kept driving, the CHG light went out. Then came back on at about the halfway mark. dash lights getting dimmer as time goes on. Turn signals stopped working, but headlights seemed OK if a bit dim. After about an hour the headlights shut off. It still had enough juice to crank the engine like nothing wrong, but the lights wouldn't come on.

I called my wife she brought the truck down and I swapped batteries. Made it home allright, only about 45 minutes later than expected.

Kind of shocked to have trouble with the 'ol trouble-free Datsun. Tomorrow I guess I need to replace the alternator brushes or something

That happened to me once. A mate and I did a spur of the moment 400km road trip one tuesday afternoon. The charge light came on if we went below 50mph. Wasn't a problem on the open road. (we were sitting on 80 most of the way) But when we hit the city, the traffic bought us undone. We had to sleep i the car. Still a cool adventure.

yer, I kept driving because... it was snowing lightly all day today. Too cold to sleep in the car !!! but I thought about it.

It snowed 2-inches overnight in Portland, Oregon. Surprise! Was all melted by mid-afternoon thankfully. I have those ADVAN A032 tires...

It's could be your external voltage regulator or the brushes on your alternator.
You took a run to Oregon for parts? Rats.
I could have put in an order.

me too, though it was nothing too sinister, just the alternator bracket that loosened, the belt slipped but did not squeal... so the alt. could not really charge, only found the problem the next day when I tried to remove it... re-tightened and all was fine and dandy..

Yeah sounds like Regulator but could be simple, as the previous post said.

happened to me twice, once was the alternator (burnt out the fuseabl;e link and soem wiring when it shorted out internally), other time 2 of the 3 alt surrport brackets snapped off. just the top one holding it on.